[sdiy] Parallel 8 Bit DACS?

[ezion]

</lurk mode>
Hi Jack
Don't get your first question completely but you might want to look
for R2R DA circuits.

As for adding VCA and VCF no magic but a "D" or "AD" type Envelope
plus VCA/VCF definitely works wonders, even better if you put a
distortion or wavefolder in front of it.
But ideally you want this on individual sounds not on the mix.
For cymbals and high-hat I find just a lonely VCF is usually enough.

A wave folder offers more compression than a traditional distortion.
The basic receipt for a wave folder: one 072 opamp, 2xLED and 3x10k resistors.
hookup:
Assuming symmetric supply for the opamp.
R1 from signal input to opamp +
R2 from signal input to opamp -
R3 as feedback resistor from opamp - to opamp out.
The 2 LED anti-parallel from opamp+ to GND
10n parallel to the diodes takes of the sharp edge.
33p parallel to the feedback resistor is always a good idea.
The input level sets the amount of drive.

Expect a wide variety of electronic drum sounds from a single acoustic
drum sample.
Just me 2 cents
<lurk mode>
Groetjes Theo


On Wed, Nov 20, 2013 at 2:35 PM, Jack Jackson <jackdamery at hotmail.co.uk> wrote:
> I'm investigating the world of drum machines and EPROMs. I quite like the idea of a DAC with parallel inputs and +/- output as per the DAC0800. I can't find any implementations of it though, apart from the datasheet. First question:- Is there a similar DAC that might better suit this purpose?
>
> As far I understand it, a fairly standard implementation for a drum machine would be an oscillator driving a parallel-out binary counter fed into an EPROMs address inputs with the EPROMs outputs fed into the the DACs parallel inputs. Like so:
>
> Oscillator -> Binary counter -> EPROM -> DAC
>
> Second question, in terms of EPROMs I believe it would be easier to use a Flash EPROM, which is electrically erased and programmed (as explained on this page: http://www.arlabs.com/help.htm ). Could one use a PIC style programmer to programme these? The Linn drum .bin files I found online seem to contain HEX code as you would programme a PIC IC with.
>
> Last question: Is there any magic to using this topology, and also analogue VCA and filtering, over using samples of original drum machines?
>
> Best Regards,
> Jack
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy